/* -*- Mode: C; c-basic-offset:8 ; indent-tabs-mode:t -*- */
/*
 * Linux usbfs backend for libusb
 * Copyright (C) 2007-2009 Daniel Drake <dsd@gentoo.org>
 * Copyright (c) 2001 Johannes Erdfelt <johannes@erdfelt.com>
 * Copyright (c) 2012-2013 Nathan Hjelm <hjelmn@mac.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "config.h"

#include <assert.h>
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/utsname.h>
#include <sys/socket.h>
#include <unistd.h>
#include <libudev.h>

#include "libusb.h"
#include "libusbi.h"
#include "linux_usbfs.h"

/* udev context */
static struct udev *udev_ctx = NULL;
static int udev_monitor_fd = -1;
static int udev_control_pipe[2] = {-1, -1};
static struct udev_monitor *udev_monitor = NULL;
static pthread_t linux_event_thread;

static void udev_hotplug_event(struct udev_device* udev_dev);
static void *linux_udev_event_thread_main(void *arg);

int linux_udev_start_event_monitor(void)
{
    int r;

    assert(udev_ctx == NULL);
    udev_ctx = udev_new();
    if (!udev_ctx) {
        usbi_err(NULL, "could not create udev context");
        return LIBUSB_ERROR_OTHER;
    }

    udev_monitor = udev_monitor_new_from_netlink(udev_ctx, "udev");
    if (!udev_monitor) {
        usbi_err(NULL, "could not initialize udev monitor");
        goto err_free_ctx;
    }

    r = udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, "usb", 0);
    if (r) {
        usbi_err(NULL, "could not initialize udev monitor filter for \"usb\" subsystem");
        goto err_free_monitor;
    }

    if (udev_monitor_enable_receiving(udev_monitor)) {
        usbi_err(NULL, "failed to enable the udev monitor");
        goto err_free_monitor;
    }

    udev_monitor_fd = udev_monitor_get_fd(udev_monitor);

    /* Some older versions of udev are not non-blocking by default,
     * so make sure this is set */
    r = fcntl(udev_monitor_fd, F_GETFL);
    if (r == -1) {
        usbi_err(NULL, "getting udev monitor fd flags (%d)", errno);
        goto err_free_monitor;
    }
    r = fcntl(udev_monitor_fd, F_SETFL, r | O_NONBLOCK);
    if (r) {
        usbi_err(NULL, "setting udev monitor fd flags (%d)", errno);
        goto err_free_monitor;
    }

    r = usbi_pipe(udev_control_pipe);
    if (r) {
        usbi_err(NULL, "could not create udev control pipe");
        goto err_free_monitor;
    }

    r = pthread_create(&linux_event_thread, NULL, linux_udev_event_thread_main, NULL);
    if (r) {
        usbi_err(NULL, "creating hotplug event thread (%d)", r);
        goto err_close_pipe;
    }

    return LIBUSB_SUCCESS;

err_close_pipe:
    close(udev_control_pipe[0]);
    close(udev_control_pipe[1]);
err_free_monitor:
    udev_monitor_unref(udev_monitor);
    udev_monitor = NULL;
    udev_monitor_fd = -1;
err_free_ctx:
    udev_unref(udev_ctx);
    udev_ctx = NULL;
    return LIBUSB_ERROR_OTHER;
}

int linux_udev_stop_event_monitor(void)
{
    char dummy = 1;
    int r;

    assert(udev_ctx != NULL);
    assert(udev_monitor != NULL);
    assert(udev_monitor_fd != -1);

    /* Write some dummy data to the control pipe and
     * wait for the thread to exit */
    r = usbi_write(udev_control_pipe[1], &dummy, sizeof(dummy));
    if (r <= 0) {
        usbi_warn(NULL, "udev control pipe signal failed");
    }
    pthread_join(linux_event_thread, NULL);

    /* Release the udev monitor */
    udev_monitor_unref(udev_monitor);
    udev_monitor = NULL;
    udev_monitor_fd = -1;

    /* Clean up the udev context */
    udev_unref(udev_ctx);
    udev_ctx = NULL;

    /* close and reset control pipe */
    close(udev_control_pipe[0]);
    close(udev_control_pipe[1]);
    udev_control_pipe[0] = -1;
    udev_control_pipe[1] = -1;

    return LIBUSB_SUCCESS;
}

static void *linux_udev_event_thread_main(void *arg)
{
    char dummy;
    int r;
    struct udev_device* udev_dev;
    struct pollfd fds[] = {
        {.fd = udev_control_pipe[0],
         .events = POLLIN},
        {.fd = udev_monitor_fd,
         .events = POLLIN},
    };

    usbi_dbg("udev event thread entering.");

    while (poll(fds, 2, -1) >= 0) {
        if (fds[0].revents & POLLIN) {
            /* activity on control pipe, read the byte and exit */
            r = usbi_read(udev_control_pipe[0], &dummy, sizeof(dummy));
            if (r <= 0) {
                usbi_warn(NULL, "udev control pipe read failed");
            }
            break;
        }
        if (fds[1].revents & POLLIN) {
            usbi_mutex_static_lock(&linux_hotplug_lock);
            udev_dev = udev_monitor_receive_device(udev_monitor);
            if (udev_dev)
                udev_hotplug_event(udev_dev);
            usbi_mutex_static_unlock(&linux_hotplug_lock);
        }
    }

    usbi_dbg("udev event thread exiting");

    return NULL;
}

static int udev_device_info(struct libusb_context *ctx, int detached,
                struct udev_device *udev_dev, uint8_t *busnum,
                uint8_t *devaddr, const char **sys_name) {
    const char *dev_node;

    dev_node = udev_device_get_devnode(udev_dev);
    if (!dev_node) {
        return LIBUSB_ERROR_OTHER;
    }

    *sys_name = udev_device_get_sysname(udev_dev);
    if (!*sys_name) {
        return LIBUSB_ERROR_OTHER;
    }

    return linux_get_device_address(ctx, detached, busnum, devaddr,
                    dev_node, *sys_name);
}

static void udev_hotplug_event(struct udev_device* udev_dev)
{
    const char* udev_action;
    const char* sys_name = NULL;
    uint8_t busnum = 0, devaddr = 0;
    int detached;
    int r;

    do {
        udev_action = udev_device_get_action(udev_dev);
        if (!udev_action) {
            break;
        }

        detached = !strncmp(udev_action, "remove", 6);

        r = udev_device_info(NULL, detached, udev_dev, &busnum, &devaddr, &sys_name);
        if (LIBUSB_SUCCESS != r) {
            break;
        }

        usbi_dbg("udev hotplug event. action: %s.", udev_action);

        if (strncmp(udev_action, "add", 3) == 0) {
            linux_hotplug_enumerate(busnum, devaddr, sys_name);
        } else if (detached) {
            linux_device_disconnected(busnum, devaddr, sys_name);
        } else {
            usbi_err(NULL, "ignoring udev action %s", udev_action);
        }
    } while (0);

    udev_device_unref(udev_dev);
}

int linux_udev_scan_devices(struct libusb_context *ctx)
{
    struct udev_enumerate *enumerator;
    struct udev_list_entry *devices, *entry;
    struct udev_device *udev_dev;
    const char *sys_name;
    int r;

    assert(udev_ctx != NULL);

    enumerator = udev_enumerate_new(udev_ctx);
    if (NULL == enumerator) {
        usbi_err(ctx, "error creating udev enumerator");
        return LIBUSB_ERROR_OTHER;
    }

    udev_enumerate_add_match_subsystem(enumerator, "usb");
    udev_enumerate_scan_devices(enumerator);
    devices = udev_enumerate_get_list_entry(enumerator);

    udev_list_entry_foreach(entry, devices) {
        const char *path = udev_list_entry_get_name(entry);
        uint8_t busnum = 0, devaddr = 0;

        udev_dev = udev_device_new_from_syspath(udev_ctx, path);

        r = udev_device_info(ctx, 0, udev_dev, &busnum, &devaddr, &sys_name);
        if (r) {
            udev_device_unref(udev_dev);
            continue;
        }

        linux_enumerate_device(ctx, busnum, devaddr, sys_name);
        udev_device_unref(udev_dev);
    }

    udev_enumerate_unref(enumerator);

    return LIBUSB_SUCCESS;
}

void linux_udev_hotplug_poll(void)
{
    struct udev_device* udev_dev;

    usbi_mutex_static_lock(&linux_hotplug_lock);
    do {
        udev_dev = udev_monitor_receive_device(udev_monitor);
        if (udev_dev) {
            usbi_dbg("Handling hotplug event from hotplug_poll");
            udev_hotplug_event(udev_dev);
        }
    } while (udev_dev);
    usbi_mutex_static_unlock(&linux_hotplug_lock);
}

